Ozaki didn't killed his wife, Kyouko was already dead at that moment, or at least, she was not human anymore. Still, I did felt sorry for her, she doesn't deserved that. But also still my favorite part, since it was heart-pounding.
Well, I don't like Muroi because: First, he was too kind, second, he betrayed Ozaki, and third, the most important of all, he killed my favorite character, Hammer-man (don't know his name, he was the old man with long beard and huge muscles). I think Sunako had lived enough. What I didn't like about her was her acting like she understands life and death more than anyone, her lecturing about it, and her pride. She should have died of torture by Hammer-man.
Though, I get what you're saying. In the end, humans were the savage ones, not the Shiki. They didn't even think twice of killing Muroi's family even though they were humans just like them.